Scientists create cloned embryos from adult monkeys

The work, led by Shoukhrat Mitalipov, a Russian-born scientist at the Oregon National Primate Research Centre in Beaverton, promises to revolutionise the efficiency by which scientists can turn human eggs into cloned embryos.

This is the first time that scientists have been able to create viable cloned embryos from an adult primate - in this case a 10-year-old male rhesus macaque monkey.

The boffins have also been able to extract stem cells from some of the cloned embryos and managed to encourage these embryonic cells to develop in the laboratory into mature heart cells and brain neurons.

However, the development will not be welcomed in all quarters, with many people fearing that the relative ease of being able to perform cloning using the skin cells of an adult will increase the chances of its being applied to produce a cloned baby.

Scientists who carried out the latest primate work are believed to have tried to implant about 100 cloned embryos into the wombs of around 50 surrogate rhesus macaque mothers but have not yet succeeded with the birth of any cloned offspring.

However, one senior scientist said that this may simply be down to bad luck - it took 277 attempts, for instance, to create Dolly the sheep, the first clone of an adult mammal.

Dr Mitalipov helped initiate a new method of handling primate eggs during the cloning process, which involved fusing each egg with a nucleus taken from a skin cell of an adult primate.

He told colleagues at a scientific meeting this year that he had made two batches of stem cells from 20 cloned embryos and tests had shown they were true clones.

According to Professor Alan Trounson of Monash University in Australia, Dr Mitalipov’s findings represented the long-awaited breakthrough.

” This is ‘proof of concept’ for the primate. It has been thought by some [to be too] difficult in monkeys - and humans - but those of us who work [with] animals such as sheep and cattle thought that success rates would be much like that achieved in these species,” Professor Trounson said.

“Mitalipov’s data confirms this. They have the skills necessary and we can now move on to consider what might be able to be achieved in humans,” Professor Trounson added.

Professor Don Wolf, who led the laboratory at the Oregon National Primate Research Centre before his recent retirement, said the new method was based on a microscopic technique that does not use ultraviolet light and dyes, which appear to damage primate eggs.

“In the early days we tried to use that technique in the monkey and unbeknownst to us at the time that was basically damaging the egg. So one of the keys was to remove that step from the process,” Dr Wolf said.

“We could now produce cloned blastocysts [embryos] in the monkey at a reasonable frequency, at least a frequency that would allow us …to study the cloned blastocyst ,” he added.